The characterization of the interfacial reaction in polyamide 1010 poly(propylene)-graft-(glycidylmethacrylate) blends

Binary blends of polyamide 1010/poly(propylene) and polyamide 1010 (PA1010)/poly(propylene)-graft-(glycidyl methacrylate) (PP-g-GMA) were prepared. The epoxy groups in PP-g-GMA react with the amino end-groups in PA1010, thus a PA1010-graft-PP copolymer is formed and acts as a compatibilizer between PA1010 and PP-g-GMA. The reaction was confirmed by electron spectroscopy for chemical analysis (ESCA) and attenuated total reflection (ATR)-FTIR spectroscopic analysis, and also evaluated by the stability of the suspension obtained by dissolving the blends in formic acid and by the morphologies of the blends.

Crystallization of micelles and matrix in dilute diblock copolymer/homopolymer solutions

The crystallization, morphology, and crystalline structure of dilute solid solutions of tetrahydrofuran-methyl methacrylate diblock copolymer (PTHF-b-PMMA) in poly(ethylene oxide) (PEO) and PTHF have been studied with differential scanning calorimetry (DSC), X-ray, and optical microscopy. This study provides a new insight into the crystallization behavior of block copolymers. For the dilute PTHF-b-PMMA/PEO system containing only 2 to 7 wt % of PTHF content, crystallization of the PTHF micellar core was detected both on cooling and on heating. Compared the crystallization of the PTHF in the dilute solutions with that in the pure copolymer, it was found that the crystallizability of the PTHF micellar core in the solution is much greater than that of the dispersed PTHF microdomain in the pure copolymer. The stronger crystallizability in the solution was presumably due to a softened PMMA corona formed in the solution of the copolymer with PEG. However, the "soft" micelles formed in the solution (meaning that the glass transition temperatures (T-g) of the micelle is lower than the T-m of the matrix phase) showed almost no effects on the spherulitic morphology of the PEO component, compared with that of the pure PEO sample. In contrast, significant effects of the micelles with a "hard" PMMA core (meaning that the T-g of the core is higher than the T-m of the PTHF homopolymer) on the nucleation, crystalline structure, and spherulitic morphology were observed for the dilute PTHF-b-PMMA/PTHF system. (C) 1998 John Wiley & Sons, Inc.

Effect of the core-shell latex polymer content on the compatibility, morphology and mechanical properties of PC/PBA-cs-PMMA blends

The toughening effect of the content of a core-shell poly(butyl acrylate)/poly(methyl methacrylate) latex polymer (PBA-cs-PMMA) on the mechanical properties, morphology and compatibility of its blends with polycarbonate(PC), i.e., PC/PBA-cs-PMMa, was studied. The mechanical properties of the blends are strongly affected by varying the content of PBA-cs-PMMA in the blend. When the PBA-cs-PMMA content is only 5 wt.-%, the impact strength of PC/PBA-cs-PMMA is almost 19 times as high as that of pure PC, indicating that PBA-cs-PMMA is a very good impact modifier for PC. With increasing interphacial layer thickness and decreasing interphacial tension, the interphacial activity becomes more and more effective and, at the same time, miscibility increases too.

Effects of the compatibilizer PP-g-GMA on morphology and mechanical properties of PP/PC blends

Effects of the compatibilizer polypropylene grafted with glycidyl methacrylate(PP-g-GMA) on the morphology, thermal, rheological and mechanical properties of polypropylene and polycarbonate blends (PP/PC) were studied. It was found that the addition of PP-g-GMA significantly changed their morphology. The mean size of domains reduced from 20 mu m to less than 5 mu m. The dispersed domain size is also strongly dependent upon the content of PP-g-GMA. The interfacial tension of PP/PC/PP-g-GMA (50/30/20) is only about one-tenth of PP/PC (70/30). The crystallization temperature of PP in PP/PC/PP-g-GMA is 5-8 degrees C higher than that of PP in PP/PC blends. Characterization studies based on mechanical properties, differential scanning calorimetry, rheology and morphological evidence obtained by using scanning electron microscopy support the hypothesis that an in-situ copolymer PP-g-PC was formed during the blending process. (C) 1997 Elsevier Science Ltd.

Morphological studies of polyamide 1010/polypropylene blends

Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the morphology of blends of PA1010 and polypropylene (PP) compatibilized with polypropylene grafted with glycidyl methacrylate (PP-g-GMA). It is found that the morphologies are dependent on the content of glycidyl methacrylate in PP-g-GMA and the mixing time. The size of the dispersed PP particles decreases as the content of GMA in the PP-g-GMA increases for binary blends of PA1010 and PP-g-GMA. Similar results are obtained for changing the mixing time. Ternary blends of PA1010, PP, and PP-g-GMA indicate that morphologies depend on the content of glycidyl metyacrylate in the PP-g-GMA and the miscibility of PP and PP-g-GMA. By changing the content of GMA in PP-g-GMA, it was possible to introduce significant changes of morphology. A matrix removal TEM method is used to investigate the interfacial structure of PA1010/PP blends containing PP-g-GMA as a compatibilizer. This technique shows the reaction product between PA1010 and PP-g-GMA to be located at interface as a surrounding layer around domain particles. SEM observation on the interface shows that the adhesion between PA1010 and pure PP is very weak and their interface boundary is sharp. For the samples of PA1010 and PP-g-GMA, it was found that the interface was not so obvious, and the reaction between PA1010 and PP-g-GMA strengthens the interface significantly. (C) 1997 Elsevier Science Ltd.

Morphology, mechanical properties and interfacial behaviour of PA1010/PP/PP-g-GMA ternary blends

Morphology, mechanical properties, and interfacial interaction of polyamide 1010/polypropylene (PA1010/ PP) blends compatibilized with polypropylene grafted with glycidyl methacrylate (PP-g-GMA) were studied. It was found that the size of the PP domains, tensile and impact strength of ternary blends, and adhesion fracture energy between two layers of PA1010 and PP were all significantly dependent on the PP-g-GMA contents in the PP layer. Correlations between morphology and related properties were sought. The improvements in properties have been attributed to chemical and physical interaction occurring between PA1010 and PP-g-GMA. (C) 1997 Elsevier Science Ltd.

Crystallization kinetics in mixtures of poly(epsilon-caprolactone) and poly(styrene-co-acrylonitrile)

Isothermal crystallization kinetics in the miscible mixtures of poly(epsilon-caprolactone) (PCL) and poly(styrene-co-acrylonitrile) (SAN) have been investigated as a function of the composition and the crystallization temperature by optical microscopy. The radial growth rates of the spherulites have been described by a kinetic equation including the interaction parameter and the free energy for the formation of secondary crystal nuclei. Fold surface free energies decrease slightly with the increase of SAN content. The experimental findings show that the influence of the glass transition temperature of the mixture, which is related to the chain mobility, on the rate of crystallization predominates over the influence of the surface free energies. This indicates that the glass transition temperature of the mixture should be of more importance, so that the growth rates decrease when the content of the noncrystallizable component increases. In addition, the Flory-Huggins interaction parameter obtained by fitting the kinetic equation with experimental data is questionable.

Asymmetric polymerization of the mixture of TrMA and MMA initiated by chiral complexes

A mixture of triphenylmethyl methacrylate (TrMA) and methyl methacrylate (MMA) was polymerized with chiral anionic initiator, such as fluorenyl lithium-(-)-sparteine [FlLi-(-)-Sp] and fluorenyl lithium-(+)-2S,3S-dimethoxy-1,4-bis(dimethylamino) butane [FlLi-(+)-DDB] in toluene at -78 degrees C. The results show that after the stable helix formed, when FlLi-(+)-DDB was used as the initiator, TrMA and MMA could be copolymerized, whereas when FlLi-(-)-Sp was used, the two monomers tended to be selectively polymerized into two polymers. This phenomenon has been explained by the existence of helix-selective polymerization. (C) 1997 John Wiley & Sons, Inc.

Study of the blends containing core-shell latex polymer

Polycarbonate (PC) and a core-shell latex polymer composed of poly(butyl acrylate) and poly(methyl methacrylate) (PBA-cs-PMMA) as core and shell, respectively, were mixed using a Brabender-like apparatus under different conditions. The mechanical properties, the morphology and the processability of the blends were investigated. Because of the good compatibility of PC and PMMA, even dispersion of PBA-cs-PMMA in PC matrix and good adhesion between the components have been achieved. PBA-cs-PMMA is thus a very good impact modifier for PC. The toughening mechanism is both cavitation and shear yielding, as indicated by SEM observation. (C) 1997 Elsevier Science Ltd.

Morphology, thermal behavior, and mechanical properties of PA1010/PP and PA1010/PP-g-GMA blends

The modification of polypropylene (PP) was accomplished by melt grafting glycidyl methacrylate (GMA) on its molecular chains. The resulting PP-g-GMA was used to prepare binary blends of polyamide 1010 (PA1010) and PP-g-GMA. Different blend morphologies were observed by scanning electron microscopy (SEM) according to the nature and content of PA1010 used. Comparing the PA1010/PP-g-GMA and PA1010/PP binary blends, the size of the domains of PP-g-GMA were much smaller than that of PP at the same compositions. It was found that mechanical properties of PA1010/PP-g-GMA blends were obviously better than that of PA1010/PP blends, and the mechanical properties were significantly influenced by wetting conditions for uncompatibilized and compatibilized blends. A different dependence of the flexural modulus on water was found for PA1010/PP and PA1010/PP-g-GMA. These behaviors could be attributed to the chemical interactions between the two components and good dispersion in PA1010/PP-g-GMA blends. Thermal and rheological analyses were performed to confirm the possible chemical reactions taking place during the blending process. (C) 1997 John Wiley & Sons, Inc.

Morphological, thermal, and mechanical properties of polypropylene/polycarbonate blend

This work deals with the effect of compatibilizer on the morphological, thermal, rheological, and mechanical properties of polypropylene/polycarbonate (PP/ PC) blends. The blends, containing between 0 to 30 vol % of polycarbonate and a compatibilizer, were prepared by means of a twin-screw extruder. The compatibilizer was produced by grafting glycidyl methacrylate (GMA) onto polypropylene in the molten state. Blend morphologies were controlled by adding PP-g-GMA as compatibilizer during melt processing, thus changing dispersion and interfacial adhesion of the polycarbonate phase. With PP-g-GMA, volume fractions increased from 2.5 to 20, and much finer dispersions of discrete polycarbonate phase with average domain sizes decreased from 35 to 3 mu m were obtained. The WAXD spectra showed that the crystal structure of neat PP was different from that in blends. The DSC results suggested that the degree of crystallization of PP in blends decreased as PC content and compatibilizer increased. The mechanical properties significantly changed after addition of PP-g-GMA. (C) 1997 John Wiley & Sons, Inc.

Synthesis of a series of chiral copolymers with azo groups and investigations of reversible liquid crystalline alignment induced by the LB films of these materials

A series of liquid crystalline copolymers, poly{2-hydroxyethyl methacrylate}-co-{6-[4-(S-2-methyl-1-butyloxycarbonylphenylazo)phenoxy]hexyl methacrylate} with an azobenzene moiety as photoreactive mesogenic unit, was prepared and investigated by using DSC, polarized optical microscopy and X-ray diffraction. The results show that these polymers exhibit smectic phases. Z-type Langmuir-Blodgett films of these copolymers were successfully deposited onto calcium fluoride and quartz. Reversible homeotropic and planar liquid crystal alignments were induced by using the photochromism of the LB films of one of the copolymers containing 20.6 mol % of the azo unit.

The chemistry of alpha-oxo ketene cyclic dithioacetal .36. Studies on silica G catalyzed decomposition of adducts of beta,beta-1,3-propylenedithio-alpha,beta-unsaturated arylketones with grignard reagents

beta, beta-1, 3-Piopylenedithio-alpha, beta-unsaturated arylketones 2 via chemoselective 1,2-addition with allyl or benzyl Grignard reagents afforded the corresponding carbinols 3 and 4. Catalysed by silica gel, the carbinols 3 and 4 were converted to the beta,gamma-unsaturated arylketones 5, 6. The mechanism and reaction condition were discussed.

Synthesis of lanthanide-alkylaluminium bimetallic complexes and studies on their catalytic activities for polymerization of some polar monomers

Three new lanthanide (Ln)-alkylaluminium (Al) bimetallic complexes with the formula [(mu-CF3CO2)(2)Ln(mu-CF3CHO2)AIR(2) . 2THF](2) (Ln = Nd, Y, R=i-C4H9 (i-Bu); Ln=Eu, R=C2H5(Et); THF=tetrahydrofuran) were synthesized by the reaction of Ln(CF,CO,), (Ln=Nd, Y) with HAI (i-Bu)(2) and of Eu(CF3CO2)(3) with AlEt(3), respectively. Their crystal structures were determined by X-ray diffraction at 233 K. [(mu-CF3CO2)(2)Nd (mu-CF3CHO2)Al(i-Bu)(2) . 2THF](2) (Nd-Al) and [(mu-CF3CO2)(2)Y(mu-CF3CHO2)Al(i-Bu)(2) . 2THF](2) (Y-Al) are isomorphous and crystallize in space group with a=12.441(3) Angstrom [12.347(5) Angstrom for Y-Al], b=12.832(3) Angstrom [12.832(4) Angstrom], c=11.334(3) Angstrom [11.292(8) Angstrom], alpha=104.93 (2)degrees [104.45(4)degrees], beta=98.47(2)degrees [98.81(4)degrees], gamma=64.60(2)degrees [64.30(3)degrees], R=0.519 [0.113], R(w)=0.0532 [0.110], Z=1 and [(mu-CF3CO2)(2)Eu(CF3CHO2)AlEt(2) . 2THF](2)(Eu-Al) in space group P2(1)/n with a=11.913(6) Angstrom, b=14.051(9) Angstrom, c=17.920(9) Angstrom, alpha=101.88(11)degrees, beta=gamma=90 degrees, R=0.0509, R(w)=0.0471 and Z=2. The six CF3CO2- (including CF3CHO2-) of each complex, among which pairs are equivalent, coordinated to Ln and Al in three patterns: (A) the two oxygen atoms in one of the three CF3CO2- type coordinated to two different Ln; (B) the two oxygen atoms in the second of CF3CO2- type coordinated to Ln and Al, respectively; (C) one of the two oxygen atoms in the third CF3CO2- type bidentately coordinated to two Ln and another oxygen coordinated to Al and one of the two Ln, respectively. Unlike types A and B, in type C the carboxyl carbon with a hydrogen atom bonded to it was found to appear as an sp(3)-hybridized configuration rather than an sp(2)-one. 1D and 2D NMR results further confirmed the existence of such a disproportionated CF3CHO2- ligand. Methyl methacrylate (MMA) and epichlorohydrin (ECH) could be polymerized by Y-Al or Eu-Al as a single-component catalyst and highly syndiotactic poly(MMA) was obtained. THF could also be polymerized by Y-Al in the presence of a small amount of ECH.

Dynamic mechanical properties of interpenetrating polymer networks based on polyacrylates and epoxy

Interpenetrating polymer networks (IPNs) based on polyacrylate (poly(polyethylene glycol diacrylate), PEGDA) and epoxy(diglycidyl ether of bisphenol A, DGEBA) were prepared simultaneously Dynamic mechanical properties of the SINs (simultaneous interpenetrating networks) with various compositions were studied. Enhanced mechanical properties were found in this case. From the point of view of pre-swollen networks, all of the PEGDA/DGEBA IPNs were composed of the individual pre-swollen networks. A micro-phase segregation system was produced in the SIN. Glass transition temperatures shifted inward, which was attributed to molecular packing effects or mutual-entanglements of molecular segments among the individual pre-swollen networks. In accordance with the additivity of properties, namely the parallel model, the entanglement density between the two polymer networks reached its maximum at 50/50 PEGDA/DGEBA IPN.